Actions
Glucosamine is thought to stimulate chondrocyte & synoviocyte metabolism. It acts as substrate for biosynthesis of chondroitin sulphate & hyaluronic acid.
Chondroitin sulphate is thought to inhibit degradative enzymes & prevent formation of fibrin thrombi in periarticular tissues.
Chondroitin & glucosamine have synergistic actions when taken together. Both may have mild anti-inflammatory effects.
Pharmacokinetics
- Glucosamine
- Approximately 87% of administered dose is absorbed in gut
- Processed primarily via renal elimination
- Dosage is 1000mg/day to 1500mg/day (500mg tablets). Higher doses may be required in diabetics, patients with peptic ulcer disease & obese patients
- Chondroitin sulphate
- 70% absorbed
- Dosage is 1200mg/day
Effects
Randomized, double blinded, placebo controlled clinical trials suggest that glucosamine salts are efficacious in management of osteoarthritis without any side effects or toxicity. trials have had short followup however.
Some authors have claimed that chondroitin also leads to ↑ in cartilage height on XR.
actions of chondroprotective agents take longer than NSAIDs but there may be continued improvements, whereas NSAIDs reach their peak of effectiveness within around week.
These agents have not been proved to be chondroprotective in hip.
Complications
Serious complications are very rare, & occur significantly less often than NSAIDs. Glucosamine may cause GI upset